example.rb

require 'celluloid/io'

class EchoServer
  include Celluloid::IO

  def initialize(host, port)
    @server = TCPServer.new(host, port)
    run!
  end

  def run
    loop { handle_connection!(@server.accept) }
  end

  def handle_connection(socket)
    loop do
      socket.write socket.readpartial(4096)
      sleep 1
    end
  end
end

class HiEchoClient
  include Celluloid::IO

  def initialize(host, port)
    @socket = TCPSocket.new(host, port)
    run!
  end

  def msg
    'hi'
  end

  def run
    loop do
      @socket.write(msg)
      puts @socket.readpartial(4096)
    end
  end
end

class ByeEchoClient < HiEchoClient
  def msg
    'bye'
  end
end

host = '127.0.0.1'
port = 1234

server = EchoServer.new(host, port)
c1 = HiEchoClient.new(host, port)
c2 = ByeEchoClient.new(host, port)

trap('INT') do
  [server, c1, c2].each(&:terminate)
  exit
end

sleep

this_terminates.rb

require 'celluloid/io'

class EchoServer
  include Celluloid::IO

  def initialize(host, port)
    @server = TCPServer.new(host, port)
    run!
  end

  def run
    loop { handle_connection!(@server.accept) }
  end

  def handle_connection(socket)
    loop do
      socket.write socket.readpartial(4096)
      sleep 1
    end
  end
end

class HiEchoClient
  include Celluloid::IO

  def self.inherited(sub)
    sub.send(:include, Celluloid::IO)
  end

  def initialize(host, port)
    @socket = TCPSocket.new(host, port)
    run!
  end

  def msg
    'hi'
  end

  def run
    loop do
      @socket.write(msg)
      puts @socket.readpartial(4096)
    end
  end
end

class ByeEchoClient < HiEchoClient
  def msg
    'bye'
  end
end

host = '127.0.0.1'
port = 1234

server = EchoServer.new(host, port)
c1 = HiEchoClient.new(host, port)
c2 = ByeEchoClient.new(host, port)

trap('INT') do
  [server, c1, c2].each(&:terminate)
  exit
end

sleep

For those coming from elsewhere, this gist is an example for celluloid/celluloid-io#22.